2 Answers
2

Mount it off the floor but with plenty of room for cooling air to circulate. Ensure it is not drawing air in over a surface on which dust settles. Regularly clean dust from the top and air intakes of the NAS.

There are several solutions for this, though some of them may not be safe.

You can put vent filters, something like this:

Note that these filters may reduce the amount of the air circulation inside the device case.

The most recommended solution (in my opinion of course), is to leave the vents as they should be, and place the NAS on a table or something, but NOT directly/close to the floor/under the table.

The only thing that is required by you, is to clean the vents from dust every month (or even less. It depends on how much dust you got in your area)
Make sure to clean the vents with a can of compressed air.

is compressed air better then using a vacuum? (or maybe a combination of both would be best).
–
epelegApr 9 '11 at 7:40

also is it recommended that the device be shut down while being cleaned ?
–
epelegApr 9 '11 at 7:41

Compressed air is better than vacuum, because it will reach for more crowded areas than the vacuum. And yes, it is recommend to shut down the device while using these cleaning methods.
–
Matan EldanApr 10 '11 at 12:48

@epeleg: Take care not to spin the fans too much while cleaning as that will induce a voltage across the supply wires of the fan.
–
ThorApr 11 '13 at 20:18